SEATTLE - Thomas Rawls found out he'd be the starting running back for the Seattle Seahawks when he arrived for the game Sunday and got a message from Marshawn Lynch.

"Marshawn came up to me and said, 'Look young 'un, I'm going to pass you the torch for the day, you know what to do," Rawls said. Lynch, Seattle's top back, was ruled inactive for the game with an abdominal injury.

Rawls didn't just take the torch, he had the best game ever by a Seattle rookie running back, rushing for a team rookie record 209 yards and a touchdown score to lead the Seahawks to a 29-13 win against the San Francisco 49ers on Sunday.

"We're all just fired up about what Thomas Rawls did," Seattle coach Pete Carroll said. "To see a young guy come through and be so physical and so tough and to make the most of an opportunity."

It was the first time Seattle had a player rush for more than 200 yards since Shaun Alexander had 201 yards against Green Bay on Nov. 27, 2006. Rawls has started four games this season and has the two best rushing games for the Seahawks. The previous best was Rawls' 169 yards on Oct. 11 against Cincinnati.

Rawls' biggest play of the day, though, came on a pass in the fourth quarter. Rawls swung out of the backfield, made the catch and blew past 49ers linebacker Michael Wilhoite to go 31 yards down the left side for a touchdown.

"I think he thought I was going to go out of bounds," Rawls said. "But little did he know, I'm not going out of bounds. I'm looking for contact."

The score gave the Seahawks a 29-13 lead and effectively ended the hopes of the 49ers (3-7).

Wide receiver Tyler Lockett had a pair of touchdown catches for the Seahawks, who are 5-5 and are still alive in the playoff hunt.

San Francisco quarterback Blaine Gabbert had a decent day, going 22-of-34 passing for 264 yards and a touchdown.

"Blaine had really good poise that he showed today," 49ers coach Jim Tomsula said. "He used his feet, used his arm, got himself out of some things. He kept his eyes downfield and made some plays. I'm not into moral victories, but that was encouraging."

The Seahawks opened up a 20-0 lead in the first half, driving for touchdowns the first three times they had the ball. When Rawls wasn't running over and through the 49ers, quarterback Russell Wilson had no trouble picking apart San Francisco with the passing game. Wilson completed 12 of his 13 passes in the first half, with two touchdowns to Lockett, and finished 24 of 29 for 260 yards and three touchdowns.

Lockett doubled his career touchdown numbers before halftime. His only previous touchdown catch came in Seattle's 20-3 win at San Francisco in Week 7. Lockett's speed led to the first score, a 24-yard strike from Wilson where Lockett simply outran San Francisco's coverage.

Rawls picked up his second rushing touchdown of the season with a 2-yard run that capped a 59-yard drive in the first quarter. The score put Seattle up 13-0 after the Seahawks missed the extra point.

Lockett showed he has some power as well as speed on his second score, an 11-yard slant. Lockett pulled in the ball a few yards short of the goal line, broke a tackle and then bulled past a pair of defenders to get into the end zone.

"Everybody was clicking," Lockett said. "We made it a goal to come out here and just have fun."

San Francisco's offense finally showed some life on the last drive of the first half. After forcing Seattle to punt for the first time, the 49ers took the ball at their own 8-yard line with about 1 1/2 minutes left and drove 92 yards for their first score. Gabbert found tight end Vance McDonald for a 19-yard touchdown pass with nine seconds left in the half.

However, the 49ers twice squandered scoring chances in the third quarter, twice getting inside the 10-yard line before coming away with field goals.

"We fluttered there in the red zone. You've got to get touchdowns," Gabbert said. "Especially versus a good football team like that, you can't come away with field goals. Points are good, but touchdowns change the game."

NOTES: Seattle RB Marshawn Lynch was ruled inactive for the game with an abdominal injury. Seattle coach Pete Carroll said Lynch will see a specialist Monday. ... San Francisco DT Glenn Dorsey injured his knee on the 49ers first defensive play of the game. He was carted off the field and did not return. He'll have an MRI exam on Monday. ... Seattle failed on two extra-point attempts. Steven Hauschka missed the attempt after the Seahawks' second touchdown, and the kick was blocked after Rawls' touchdown in the fourth quarter. It was the first time the Seahawks missed an extra point since Hauschka had a kick blocked against Buffalo on Dec. 16, 2012. ... Seattle has won four straight regular-season games against the 49ers.